1. Field of the Invention
The present disclosure generally relates to compressible seals, such as the type intermediate a door and doorframe; and more particularly, to seal architectures that employ active material actuation to selectively reduce/increase the sealing force.
2. Discussion of Prior Art
Current methods and assemblies for sealing opposing surfaces such as doors and trunk lids, for example, include the use of flexible elastic membranes and structures that compress upon pressing contact of one component against another. Because of this, to provide effective sealing engagement, closure force must be sufficient to overcome any compressive forces associated with the seal assembly. Typical materials employed for seal assemblies are passive materials and generally include various forms of elastomers, e.g., foams and solids, that are formed into structures having solid and/or hollow cross sectional structures. The geometries of the cross sections are varied and may range from circular forms to irregular forms having multiple cavities, channels, slots and/or extending vanes.
Sealing assemblies are typically utilized for sound, airflow, and/or fluid management. The seals generally are exposed to a variety of conditions. For example, for vehicle applications, door seals generally are exposed to a wide range of environmental conditions such as rain, snow, sun, humidity and temperature conditions, and the like. As noted above, current materials utilized for automotive seals are generally passive. That is, other than innate changes in the modulus properties of the seal material due to aging and environmental stimuli, the stiffness and cross sectional geometries of the seal assemblies cannot be remotely changed or controlled on demand.
Of concern, conventional passive seals present a tradeoff between seal effectiveness and closure effort. That is to say, increasing the interface pressure and/or contact area of the seal can generally increase seal effectiveness; however, in sealing applications, such as in vehicle doors, the increased interface pressure and/or contact area by passive seal assemblies generally results in increased door opening and closing efforts.
Accordingly, it is desirable to have active material based seal assemblies that can be controlled and remotely changed to alter the seal effectiveness, wherein the active seal assemblies change stiffness properties on demand, for example, by changing the material's elastic modulus, or geometry by actively changing the cross-sectional shape of the seal structure. In this manner, in seal applications such as the vehicle door application noted above, door opening and closing efforts can be minimized yet seal effectiveness can be maximized by actively manipulating the seal properties.